Steam-boiler economizer and method of operating same



D. S. JACOBUS.

STEAM BOILER ECONOMIZER AND METHOD OF OPERATING SAME.

2 SHEETS-SHEET I.

IN VEN TOR.

/ ATTORNEYS.

Patented May 25,1920.

APPLICATION FILED JAN. 3, 1918.

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' where t v I An economizer cannot be protected from UNITED STATES,

PATENT OFFICE.

, DAVID S. JAOOBUS; OF JERSEY CITY, NEW JERSEY, ASSIGNOB TO BAIBCOCK &;WILCOX COMPANY, OF BAYONNE, NEW JERSEY, A CORPORATION OF NEW JERSEY.

STEAM-BOILER ECONOMIZEB-AN D METHOD OF OPERATING SAME.

oilginal application filed December 8 To all whom it may concern:

Be it known that I. DAVID S. J ACOBUS, a

' citizenof the United States residing at J ersey City, in the countyvofIiudson and State of New Jersey, have invented certain'i ew and usefulImprovements in Steam-Boiler Economizers and Methods of Operating theS'ame, of which the following is a specifi-' cation. I

The present a plication is a division of my application serial No.876.013 filed December 8, 1914. .As stated in that application,corrosion or pitting in the interior of a boileris due to elements inthe water that oxidize or otherwise affect the iron. This is oftenprevented or minimized by the addition to the water of a neutralizingreagent,

such as carbonate of soda or lime, the

plied after the first reagent is added will be only that required tomake up for any chemical action, or forthe amount that is lost .inblowing down the boiler. The reagent may be added atintervals to theboiler, say once per day,or it may be added c0ntinuously to the feedwater. If added continuously to the feed water the amount per gallon offeed water may be less than-that needed to prevent the corrosion, andthe re agent, 'or to be more exact, the resulting compound formedthrough the reagent acting on'any impurities in the feed water andthrough the presence of an excess of the reagent over that requiredtoact on the 1mpurities, may be allowed to concentrate in the boiler totheproner point: for example,

{the feed water might be treated, with two grains of the reagent pergallon which could be allowed to concentrate in the boiler to twentygrains per gallon of the reagent and the resulting compounds, and thetwenty grains er gallon might give good results he two grains per gallonwould not.

Patented-May 25, 1920.

1914, Serial No. 876,013. Divided and this application filed January 8,1918 Serial No. 210,213.'

interior corrosion "by the addition of a reagent from time to time as inaboiler as the reagent would pass directly through .the economizer withthe water; again, should the reagent be added continuously to the feedwater, the elements in the feed water cannot be made to concentrate inthe economizer in the way that they do in a boiler. In the numericalexample just given, if twenty grains were needed to prevent corrosion,it would be necessary to treat the feed water with twenty grains pergallon to properly protect the economizer, which would make thetreatment more costly than for a boiler and require the boiler to beblown down at frequent intervals to avoid over-concentration of thecontained water.

Distilled water from a condenser, or such water with only a small amountof raw or make-up water mingled with it, has been found to give troublethrough corrosion; air and carbonic acid gas in the feed water add to,or.in some cases may be the sole cause of,

corrosion.

The tendency in modern power plant.

practice is toward large size boiler units and high overloads, and tomaintain a high capacity the boiler must be kept clean on its interior,otherwise there will be tube difiiculties. It is, therefore, of extremeimportance that the boiler feed water shall be of a high degree ofpurity and to meet the present tendency the practice is to cut down theamount of make-up water, to avoid the formation of scale in the tubes,and to increase the amount from the hot well, the latter being distilledwater coming from the condensers in the plant. But feed water of thedesired purity for the boiler may cause trouble through corrosion of theeconomizer, particularly if it is one of wrought iron'or wrought steel.

The purpose of the present invention is to aid in preventinginternal andexternal corboiler units each having its individual mingling tank; andFig. 3 a side View of the individual mixing tanks. Similar referencenumerals indicate similar parts in the several views.

- In Fig. 1 I have shown a boiler of a standard design in which thenumeral 1 designates a bank of inclined generating tubes expanded intofront and rear headers. The boiler may be fired by any well-known orusual means, a chain grate stoker 2 being indicated. The gases from thefurnace flow through the boiler, as indicated by the arrows, to a flue 3leading to the uptake 4.

Located in the flue and, as shown, abovethe boiler, is an economizercomprising a low pressure stage or section 5 and a high pressure stageor section 6. These sections consist of tubes fitted into upper andlower boxes, the high pressure stage composed of wrought iron orwrought, steel tubes and headers and subjected to the action of thehottest gases, and the low pressure section composed of cast iron tubesand headers and subjected to the action of the coldest gases.

7 indicates the source of the main supply of water, such as the hot well7 to which the condensed steam from the plantis run, this beingdistilled water and practically freeof 1 chemical reagents.

From the hot well the water is pumped by a pump 8 through pipe 9 to thelow pressure section of the economizer and from said section the wateris delivered through pipe 10 into the upper part of a tank 11. As shownin Fig. 2, the water is delivered to the low pressure sections 5 throughvalved branch connections 12 leading from the supply pipe 9, and fromsaid sections the water is delivered to a common tank 11 through valvedbranch connections 13 leading to the pipe .10. Thermometers 14 areplaced in the pipes 13, these thermometers being important in theoperation of a plant as the valves 15 should be adjusted to give thedesired outlet temperatures for the low pressure sections of theeconomizers.

The tank 11 to which the 'hot water is delivered from the low pressuresections of the economizers, is provided with a series of perforatedshelves 16 over which the water is caused to flow. A relief valve 17 isplaced at the top of the tank and the air and gases released from theheated water permitted to escape therethrough, or the air and gases maybe withdrawn through a separate connection 18 to which an ejector or airpump may be connected to maintain the pressure below that of theatmosphere, if desired.

branch connections 22 into tanks 23, there being one such tank for eachboiler. The tanks 23 are preferably so arranged that any mud or sedimentin the water will settle to the bottom and can be blown off through thevalved connections 24. The purpose of the tanks 23 is to mingle the feedwater therein with water from the corresponding boiler, which boilerwater contains a certain amount of a chemical reagent which, when thewater is passed through the high pressure stages of the economizers,will assist in :preventing or minimizing corrosion of the tubes. Asshown, the boiler water 18 taken from the steam and water drums of eachboiler through a pipe 25, having valved branch connections 26, to pump27 and delivered to the corresponding mingling tank 23 through pipe 28.The pumps 27 require acomparatively small amount of power as theyovercome only the difference in pressure between the boiler and the feedwater entering through pipe 21. The mingled volume of water from eachtank 23 passes through its outlet pipe 29 to the high pressure section 6of the corresponding economizer, and from the latter through pipe 30 andbranch connections having feed valves 31 and ordinary check valves 32,into the steam and water drum. Thermometers 33 are placed in the valvedconnections 22 and in the pipes 28 and 29 to indicate the temperaturesof the feed water and boiler water entering the tanks 23, and of themingled volume leaving saidtanks. By noting the difference intemperature between the incoming and outgoing water the amount returnedfrom the boiler to the feed water may be determined.

The pipes 9, 10 and 21 are shown as openended to indicate that they maybe used for more than the two boilers shown.

The water from the hot well 7 may be at the temperature of approximately80 F., and this water is heated when it passes through the several lowpressure economizer sections. When mingled with the boiler water, thetemperature of the water in each of the tanks 23 is above a temperaturewhich will prevent sweating on the outside of the wrought ironor,wrought steel tubes of the high pressure sections 6 of theeconomizer, say for example 120 F., and this prevents or minimizescorrosion on the exterior of said tubes. As the pressure in sections 5of the economizers is com iaratively low, said sections may be made otcast iron tubes which experience has shown will withstand interiorcorrosion to a greater extent than wrought iron or wrought steel, orthis section may be made up of tubes of some other metal and, by usingtubes of the right diameter and properly spacing them, the heattransferred from the gases to the tubes may be madea maximum with aminimum draft loss.

By maintaining aproper concentration of the reagent in the boiler, thewater in the several tanks 23 may be made to contain a suilicient amountof the reagent to prevent interior corrosion of the tubes of the highpressure section. without raising the temperature of the water in saidtanks above a point which will interfere with the economy of the plant.The amount of the chemical reagent in solution in the boiler may hegraduated by adding more or less of such reagent, either intermittentlyor continuonsly. to the respective tanks 23, or b introducing it at thehot well. The. only addition of a reagent is that necessary to make upfor a leakage, for any water that may be blown away from the boilers,and for any chemical reaction which may take place within theeconomizers and boilers. The degree of concentration of the water. in

the boiler may be determined by the stand-- ard method of chemicaltitration, or by measuring the density of the water.

The invention is not, however. limited to the use-of boiler water towhich a chemical reagent has been added. In its broader aspect itincludes the return oi a certain amount of water from the boiler to theeeonomizer. \Vhere the water used for makingup for leakage and forblowing down the boilers, or what is known as the makeup water, containsin itself the necessary elements to prevent corrosion, no reagent needbe added. Whether the make-up water is one which requires the additionof reagents or a water which carries the necessary elements to preventcorrosion. the present invention, prevcntsor lessens the tendency tocorrosion in the economizer. The following example will serve to make mymeaning clear. make-up water containing 8 grains of material per gallonof a nature that will tend to stop the corrosion that occurs withdistilled Water from the condensers. The mixture of the make-up waterwith the distilled water from the condensers would contain 0.73 grainsper allon. lt'operated in the ordinary way t e water passing through theeconomizer would contain 0.73 grains per gallon of the material thatwould tend to stop corrosion, whereas the water contained in the boilermight be concentrated so as to contain say grains of the same Assumethat there is 10 per cent. of

material per gallon. If now the boiler and economizer are operated inaccordance with the present invention, and one pound of Water containing100 grains per gallon is Withdrawn from the boiler and mingled with 5pounds of the water containing (1T3 grains per gallon, the material inthe mingled Water which would pass through the economizer would amountto about 17 grains per gallon, a larger amount than the original, 0.73grains, leading to a lesser amount of interior corrosion. By practisingthe invention, therefore. the grains of matter tending to reducecorrosion in the numerical case considered is increased more than twentytimes over what would exist in ordinary practice.

In operating two or more boilers in which the Water after passingthrough the low pressure sections of the economizers is mingled inacommon tank with water drawn from all the boilers. care must beexercised to maintain the amount of conceir tration in the boilers atabout the same point. Should a materially less amount of water, inproportion to the water evaporated, be returned. from one of the boilersto the common mixing tank, the water in the boiler from which the lessamount is drawn would soon reach a higher degree of concentration thanthe other boilers. .-\ccording to the present invention, however, thenecessity ot' making a close adjustment of the water allowed to flowfrom and] boiler is eliminated for the reason that all of the watertaken from a particular boiler. and mingled with the feed water. isreturned to the same boiler from which it is withdrawn. \Vhcre achemical reagent is necessary it is preferably introduced along with themakc-up water and in that case the amount of concentration in -ach oi'the boilers may be regulated by blowing oft more or less water from theboiler. Should a boiler be accidentally blown down to an amount whichcauses the concentration of the contained water to be too low, therequired amount of reagent, in solution, may be pumped directly into theboiler.

From the foregoing description itwill be seen that I preventor minimizecorrosion of the-high pressure sections of the economizers byeliminating the air and gases from the water, and by adding a certainamount of water from the boiler containing elements which resistcorrosion.

As before stated, the drawingsare dia-. grammatic. Certain common andwellknown features such as safety valves for the economizers have notbeen shown. JRegulating the supply ofmake-upwater and maintaining theproper level of water in the hot well, as well as regulating the waterlevel in thetank 11, may be carried out in many well-known Ways. Theseare oper- Hit) ating features aside from the principles of my inventionwhich I have described.

What I claim and desire tosecure .by

Letters Patent of the United States is ""1. The method of operating aplurality tions with water from the boilers containing corrosionpreventing elements, and then forcing the mingled volumes through othercorresponding sections of the economizers at a higher pressure than thefirst sections, and thence into the corresponding boiler, whereby theWater drawn from a given boiler is returned to that boiler and corrosionof the economizer minimized through the action of the corrosionpreventing elements and the heat of the boiler water.

2. The method of operating a plurality of boilers consisting in firstpassing the main supply of water through correspom'ling economizersections, delivering the water so heated to a common tank and permittingthe air and gases to escape therefrom, dis tributing the water from saidtank to individual tanks and mingling the water in the latter with watercontaining corrosion preventing elements from the cerresponding boiler,and then forcing the mingled volumes through corresponding sections ofthe economizer at a higher pressure than the first sections, thence intothe boilers, whereby the Water drawn from a given boiler is returned tothat boiler, and corrosion of the economizer minimized through theaction of the corrosion preventing elements and the heat of the boilerwater.

3. Incombination, a plurality of steam boilers, each having a sectionaleconoinizer adapted to be heated by the waste gases, means fordelivering the main supply of water to corresponding low pressureeconomizer sections and from the latter to a common tank,individualtanks for the respective boilers, connections from said commontank to said individual tanks and from the boilers to the respectiveindividual tanks, and means for forcing the mingled volumes from theindividual tanks through the high pressure sections of the economizerssubjected to the hottest gases and thence into the corresponding boiler.I

4. In combination, a plurality of steam boilers each having a sectionaleconomizer adapted to be heated by the waste gases, means for conductingthe feed water at a low pressure through corresponding economixersections, means intermediate the economizer sections to which the heatedwater is conducted, an individual mingling tank for each boiler,connections from said common tank and from the boilers to said lastnamedtanks, and means for forcing the mingled volumes from the individualtanks through corresponding sections of the economizers at a higherpressure than the first sections and thence into the boilers.

5. In combination, a plurality of steam boilers, each having a sectionaleconomizer adapted to be heated by the waste gases, means for deliveringthe main supply of water to corresponding low pressure economizersections and from the latter to a common tank, individual tanks for therespective boilers, connections from said common tank to said individualtanks and from the boilers to the respective individual tanks, and meansfor forcing the mingled volumes from the individual tanks through thehigh pressure sections of the economizers subject ed to the hottestgases and thence into the corresponding boiler, and thermometers in theconnections leading to and from said individual tanks.

6. In combination, a plurality of steam boilers, each having a sectionaleconomizer adapted to be heated by the waste gases, means for deliveringthe main supply of water to corresponding low pressure economizersections and from the latter to a common tank, individual tanks for therespective boilers, connections from said common tank to said individualtanks and from the boilers to the respective individual tanks, means forforcing the mingled volumes from the individual tanks through the highpressure sections of the economizers subjected to the hottest gases andthence into the corresponding boiler, and connections for removing anymud or sediment which may collect in the individual tanks.

In testimony whereof I have hereunto signed my name in the presence oftwo subscribing witnesses.

DAVID S. JACOBUS.

\Vitnesses:

HERMAN FISCHER, HERMAN B. SMITH.

